Whether it is in anticipation of or post physical activity, stretching is an important exercise for a person to employ. Generally, stretching includes intentionally or deliberately flexing or extending a joint and lengthening a specific muscle or tendon (or muscle group) in order to improve a muscle's felt elasticity, length, or tension relationship and/or achieve comfortable muscle tone. The result is a restoration of appropriate muscle length, leading to a feeling of increased muscle control, flexibility, and range of motion. Stretching is also used therapeutically to alleviate cramps and chronically shortened, dysfunctional muscles due to maladaptive joint positions such as high heel shoes and prolonged desk sitting. In its most basic form, stretching is a natural and instinctive activity; thus, it is performed by humans. Increasing flexibility through stretching is one of the basic tenets of physical fitness. Stretching is also common for athletes to stretch before (for warming up) and after various exercises to reduce risk of injury and increase performance. In sports medicine, it has been found that limitations in normal ankle dorsiflexion range of motion (ROM) from tight calf muscles is directly linked to pathologies such as Achilles tendonitis, calf tears and plantar fasciitis (Muir, Chemsworth, Vandervoort 1999). Stretching can also be dangerous when performed incorrectly. There are many techniques for stretching in general, but depending on which muscle group is being stretched, some techniques may be ineffective or detrimental, even to the point of causing hypermobility, instability, or permanent damage to the tendons, ligaments, and muscle fiber.
Stretching a muscle in a user's lower extremity, e.g., the calf or ankle area near the Achilles tendon, can be particularly problematic for many users based on the location of the muscle, the passive resistance of the muscle and the very nature of the lever system the calf muscle is exerting force upon. Specifically, the calf is the back portion of the lower leg and muscles within the calf correspond to the posterior compartment of the leg. The two largest muscles within this compartment are known together as the calf muscle and attach to the heel via the Achilles tendon. These muscles exert force upon the heel bone which in turn drives the ball of the foot (metatarsal heads) into the ground with mechanical advantage due to force being driven through a type 2 lever system (there are Type 1, 2 and 3 lever systems in the human body). In order to drive this lever system in reverse, thus driving the ball of the foot away from the ground via the heel bone fulcrum and in turn exerting a lengthening force upon the calf complex, the heel bone must be held tightly to avoid translation and allow leveraged force to be exerted upon the calf; much like a beer bottle opener must be fixed firmly on the lip of the bottle neck to allow the cap to be levered upward. For this reason, the heel bone must be held firmly at or above the Achilles insertion for true leveraged force to be applied through both the ball of the foot and heel bone simultaneously. Although other stretching devices may provide body weight force to the ball of the foot, no other device fixes the heel above its fulcrum point to allow the body to drive over the heel and provide true mechanical advantage and maximal torque to overcome passive calf muscle resistance.
Several known lower extremity stretching devices are part of larger stretching devices that are aimed to stretch a variety of different muscle groups of a user's body. As such, theses devices are large and cumbersome, in addition to being time- and cost-intensive in regard to the device's installation, disassembly, and maintenance. Therefore, these larger devices are commercially impracticable for most consumers. Further, these known devices also fail to provide effective retention of a user's heel or foot when engaged in the calf stretching exercises.
Other known lower extremity stretching or exercising devices may be portable and/or aimed specifically at stretching a user's calf, but these devices also suffer from several disadvantages. Specifically, these devices generally include a body supported on a round surface, wherein the body includes an inclined platform surface where a user will place his or her foot before engaging in a stretching activity. These are roller-type calf stretchers, where the foot is locked into a half moon shaped shoe holder. The user leans forward and the calf muscles stretch under body weight only, similar to dropping the heel from a step. This method provides some stretch to the calf, but does not allow a deeper leveraged stretch by retaining the heel above the fulcrum point. Furthermore, it does not allow the user to lever over the top of the heel on a fixed base as these devices rock forward which does not allow any further stretch beyond body weight. It is not easy to balance while using this stretching device. This can be extremely dangerous for the elderly and/or anyone who lacks good coordination. Moreover, the foot is not in an optimal position to get the best stretch, and the user tends to bend their knee to maintain balance rather than hyperextending it when stretching the calf. This can be very awkward to use and even difficult for elderly individuals and those with lower extremity arthritis or other painful conditions. Thus, compliance with recommended stretching is diminished significantly and therefore individuals may not improve their condition.
Other known lower extremity stretching or exercising devices, such as U.S. Pat. No. 8,360,940 (Kole et al.), include an inclined or angled foot platform with a lower heel retention portion. However, these devices are designed to accomplish multiple stretching techniques of a user's lower leg or foot. To that end, the device is intentionally designed to make the heel portion translate or adjust leading to failure when significant weight is subjected thereon. Additionally, these devices include other exercising components that prevents the user to stretch effectively. Further, these devices also do not provide an effective and comfortable means to retain a user's heel firmly above the fulcrum point which would otherwise fix the heel during the stretching process and prevents the device from shifting when in use and subject to the weight of a user.
Therefore, a need exists to overcome the problems with the prior art as discussed above.